This is like the question about getting to the center of a Tootsie Roll Pop. How many attempts does it take for them to get the origin right?

First they have to show that they can get the character himself right. 2 tries(3 if you count the TV show) and nada so far. Hopefully in the Avengers Whedon & Ruffalo will do better.

But without the gamma bomb(or something very similar), Rick Jones and Banner & Hulk both being characters and the interplay off of them with regards to each other, you simply don't have even close to a faithful origin story.

Might as well have Superman dropped here like Hyperion in the Supreme Power comic or Batman being abandoned by his parents instead of watching them get murdered or Iron Man just being built as a result of Tony Stark getting bored one day or Spider-Man being a mutant who was born with his powers and could've become another one of the X-Men. Liberties can and will be taken with all of their origins when translated to screen but for my money all the ones I just mentioned(and many others not mentioned like DD & the FF) were still highly faithful. Hulk's has never even reached anywhere near that and it really bugs me since I love the Hulk's original origin and all the subtle facets of it.